(1) Field of the Invention
The present invention relates to a multi-vision screen adapter for combining a plurality of images inputted with a corresponding number of monitoring cameras and displaying the composite image on a multi-vision screen divided into a number of subscreens corresponding to the number of the input images.
(2) Description of Related Art
Generally a multi-vision screen adapter operates PIP (Picture in Picture) system (display system capable of displaying a plurality of images simultaneously on a screen) whereby input images from several monitoring locations (commonly two or four, in some cases sixteen locations) are composed into one image, and the composite image is displayed on a multi-vision screen. In this PIP system, a plurality of locations can be monitored simultaneously simply by examining the composite image. With the PIP system, however, details in the input image cannot be examined unless it is magnified and displayed over the screen. Displaying of the input image over the whole screen makes it impossible for the operator to examine other monitoring locations concurrently, even though one monitoring location can be examined thoroughly. As a result, discovery of an unusual happening will be delayed unless it happens in front of the monitoring camera currently displayed on the screen.
Accordingly, it is a first object of the present invention to provide a multi-vision screen adapter for displaying a plurality of input images from a corresponding number of monitors simultaneously on a multi-vision screen by zoom-up magnifying any of the input images.
It is a second object of the present invention to provide a multi-vision screen adapter for zoom-up automatically detecting an unusual happening in the input image.
It is a third object of the present invention to provide a multi-vision screen adapter for zoom-up magnifying the input image when an unusual happening is detected therein.
It is a fourth object of the present invention to provide a multi-vision screen adapter of high practicability for applying zoom-up magnification, one time magnification, which is defined here as reproduction at actual size, PAN/TILT, STEP SHIFT to each subscreen of the multi-vision screen independently.
The above objects may be fulfilled by a multi-vision screen display device comprising a display screen divided into areas for displaying a plurality of input images on the areas, an image processing unit in the same number as said areas, each for receiving the input image and outputting the input image at a timing which realizes to display it on the preset area, an input image distributing unit for distributing the input images each to the preset image processing unit, and a display control unit for controlling the image processing unit to zoom-up the input image to be displayed on the desired area.
The image processing unit may be comprised of an image memory, a writing unit for writing the input image into the image memory, a reading unit for reading the image from the image memory at a timing which realizes to display the image on the preset area, and the display control unit may control a writing speed of the writing unit and a reading speed of the reading unit at the image processing unit which is designated to operate the zoom-up of the image.
The display control unit may further comprise a readout area selecting unit for selecting a size of a readout area within a scanning field of the input image, in which the readout area represents the image to be read from the scanning field and displayed on the preset area of the display screen.
The display control unit may further comprise a readout area displacing unit for displacing the readout area within the scanning field in a horizontal scanning direction and/or a vertical scanning direction at a fixed speed.
The display control unit may further be comprised of a readout area replacing unit for dividing the scanning field into a plurality of subfields and replacing the subfield with another at a lapse of time, thereby the readout area is selected on the replacing subfield.
The above objects may be fulfilled by a multi-vision screen display device having a same number of processing units as subscreens of a display screen, the processing units processing to display an input image on a display area being the subscreen assigned to each processing unit, the processing unit comprising an image memory, a display magnification selecting unit for selecting a read-out area of the input image to be displayed on the display area, a writing unit for writing an image signal within the selected read-out area into the image memory at a pixel density which corresponds to a display magnification, and a reading unit for reading the image signal from the image memory at a timing which realizes to display the read-out area of the input image on the display area.
The writing unit may comprise a coordinate detecting, unit for detecting coordinates of the image signal within a scanning field at each moment, a judging unit for judging if the detected coordinates place within the read-out area of the input image, a clock frequency changing unit for changing a frequency of a sampling clock in accordance with the display magnification, a sampling unit for sampling the image signal at the frequency of the sampling clock, a horizontal address designating unit for designating a horizontal address where the image signal is written in, a vertical address designating unit for designating a vertical address where the image signal is written in, and a write controlling unit for writing the image signal sampled by the sampling unit into a write-in area of the image memory designated by the horizontal address and the vertical address when the judging unit judges that the coordinates of the image signal place within the read-out area of the input image.
The sampling unit may be an A/D converter.
The multi-vision screen display device may further comprise a unit for generating a pixel clock basing upon the inputted image signal, wherein the clock frequency changing unit is comprised of at least one divider and a switch, and it can change the display magnification at least into a zoom-up display or a one-time magnification display by having the switch select a pixel clock as the sampling clock at the zoom-up display or having the same select a division of the pixel clock by the divider as the sampling clock at the one-time magnification display.
The horizontal address designating unit may be a first counter which counts the sampling clock while the vertical address designating unit may be a second counter which counts a horizontal synchronous signal included in the image signal, in which the first counter is reset when a horizontal component of the coordinates represents a right end of the read-out area while the second counter is reset when a vertical component of the coordinates indicates a top end of the read-out area, the coordinates detected by the coordinate detecting unit.
The coordinate detecting unit may be comprised of an X coordinate counter and a Y coordinate counter, the X coordinate counter counting the pixel clock until the coordinate detecting unit is reset by the horizontal synchronous signal included in the image signal while the Y coordinate counter counting the horizontal synchronous signal until the coordinate detecting unit is reset by the vertical synchronous signal.
The display magnification selecting unit may be comprised of an output circuit for outputting coordinates of an upper left corner and a bottom right corner of the read-out area represented by the counting number of the X coordinate counter and the counting number of the Y coordinate counter.
The judging unit may be a comparator which compares the counting number of the X coordinate counter and the counting number of the Y coordinator with the coordinates from the output circuit.
The output circuit may comprise an X start register and a Y start register for holding the X coordinate of the start point and the Y coordinate of the start point respectively, the start point indicating the upper left corner of the read-out area, while an X end register and a Y end register for holding the X coordinate of the end point and the Y coordinate of the end point respectively, the end poind indicating the bottom right corner of the read-out area.
The multi-vision screen display device may further comprise a read-out area horizontal displacing unit for updating the X coordinates in the X start and the X end registers with keeping a same difference between them.
The read-out area horizontal displacing unit may be comprised of a read-out area positive displacement controlling unit for updating the X coordinates in the X start and the X end registers by increasing them at a fixed speed, a first comparator for comparing the updated X coordinate in the X end register with the right end, coordinate of read-out area of the input image at said increase of the X coordinates, a read-out area negative displacement controlling unit for updating the X coordinates in the X start and the X end registers by decreasing them at a fixed speed, a second comparator for comparing the updated X coordinate in the X start register with the left end coordinate of the read-out area of the input image at said decrease of the X coordinates, and the read-out area horizontal displacing unit may start operating the read-out area positive displacement controller when the X coordinate in the X start register coincides with the left end coordinate of the read-out area.
The multi-vision screen display device may further comprise a read-out area vertical displacing unit for updating the Y coordinates in the Y start and the Y end registers with keeping a same difference between them.
The read-out area vertical displacing unit may be comprised of a read-out area positive displacement controlling unit for updating the Y coordinates in the Y start and the Y end registers by increasing them at a fixed speed, a first comparator for comparing the updated Y coordinate in the Y end register with the top end coordinate of the read-out area of the input image at said increase of the Y coordinates, a read-out area negative displacement controlling unit for updating the Y coordinates in the Y start and the Y end registers by decreasing them at a fixed speed, a second comparator for comparing the updated Y coordinate in the Y start register with the bottom end coordinate of the read-out area at said decrease of the Y coordinates, and the read-out area vertical displacing unit may start operating the read-out area positive displacement controlling unit when the Y coordinate in the Y start register coincides with the bottom end coordinate of the read-out area.
The input image may be shot by a monitoring camera and a screen of the monitoring camera may be divided into a plurality of areas, and the output circuit may include a circuit for replacing the coordinates of the start point and the end point of the read-out area on one area, the coordinates held in the X start register, the Y start register, the X end register, and the Y end register, with the coordinates of the start and the end points of the read-out are on another area.
The multi-vision screen display device may further include an image sensor for computing a sum of a luminance signal of a pixel placing within a fixed range of the read-out area, and generating an alarm signal when a difference between the sum at a last scanning field and the sum at a current scanning field is larger than a predetermined threshold value.
The image sensor may be comprised of an adding unit for adding the luminance signal of every pixel within the fixed range of the read-out area at the current scanning field, a holding unit for holding said addition result for the sum at the last scanning field, a difference computing unit for computing the difference between the addition result held in the holding unit and the addition result from the adding unit; and an alarm signal output circuit for comparing the difference from the difference computing unit with the threshold value, then outputting the alarm signal when the difference is larger than the threshold value.
The multi-vision screen display device may further comprise a zoom-up display selection controlling unit for selecting the zoom-up display upon receipt of the alarm signal from the image sensor, a writing unit for writing an image signal within the selected read-out area into the image memory at a pixel density which corresponds to a display magnification, and a reading unit for reading the image signal from the image memory at a timing which realizes to display the read-out area of the input image on the display area.
The multi-vision screen display device may further comprise a connection switching unit placing between the monitoring camera and each processing unit and for replacing a connection between the monitoring camera and the processing unit with another.
The above objects may be fulfilled by a multi-vision screen display device which processes an input image from a plurality of monitoring cameras by a same number of processing units as the monitoring cameras and displaying each input images on a subscreen of a multi-vision screen simultaneously, the processing units comprising an image memory, and a display magnification selection unit for selecting a read-out area within a scanning area of a screen at the monitoring camera, the read-out area to be displayed on a display area being the subscreen assigned to the processing unit, a writing unit for writing an image signal within the read-out area into the image memory at a pixel density which corresponds to a display magnification, and a reading unit for reading the image signal from the image memory at a timing which realizes to display the, read-out area of the input image on the display area.
The multi-vision screen display device may further comprise a read-out area replacing unit for replacing the read-out area by another and a connection switching unit for replacing a connection between the monitoring camera and the processing unit by another, wherein the read-out area is determined in accordance with the connection by the connection switching unit which determines the number of the processing units where the monitoring camera provides the input image.
The writing unit may comprise a coordinate detecting unit for detecting coordinates of the image signal within a scanning field at each moment, a judging unit for judging if the detected coordinates place within the read-out area of the input image, a clock frequency changing unit for changing a frequency of a sampling clock in accordance with the display magnification, a sampling unit for sampling the image signal at the frequency of the sampling clock, a horizontal address designating unit for designating a horizontal address where the image signal is written in, a vertical address designating unit for designating a vertical address where the image signal is written in, and a write controlling unit for writing the image signal sampled by the sampling unit into a write-in area of the image memory designated by the horizontal address and the vertical address when the judging unit judges that the coordinates of the image signal place within the read-out area of the input image.